Post subject: Phase shifting of a Signal Posted:
Tue Nov 01, 2005 3:31 am
How do you shift the Phase of an analog
With digital its so easy, you just put a delay of couple
of usecs and you get a phase shifted signal.
How do you do it
Post subject: Analog
phase shiftPosted: Tue Nov 01, 2005 2:22 pm
There are several
ways of shifting the phase of an analog signal:
1. Use the appropriate
length of cable: 90 degrees is one-quarter wavelength (don't forget
to include the velocity factor of the cable!)
delay lines are also a possibility at frequencies low enough that
a piece of cable would be unreasonably long. These simulate a piece
of cable by series / parallel C circuits, cascaded. Other kinds
of LC networks are also possible if you don't want constant time
3. RC Networks: the phase shift is 45 degrees at f
= 1/(2 pi RC) for a simple two-component high-pass or low-pass.
More complicated networks can be used to shape phase as a function
Obviously, some techniques (RC) are lossy,
some (transmission lines) have very little loss.
Post subject: Posted: Wed Nov
02, 2005 1:37 pm
Are you aware of any manufactureres that make
Delay lines for analog signals. It should be variable delay, not
one of those fixed -10%, 20% delays.
Post subject: Phase ShiftPosted: Thu Nov 03, 2005
I haven't checked their recent catalogs, but Data Delay
Devices Inc. used to make such things.
Post subject: Posted: Thu Nov 10,
2005 2:12 pm
i found a new way - using an all pass filter to
delay the phase. I can change the phase by varying the resistace.
Only problem is the output amplitude is not constant at my frequency
It works fine in the Khz range.